1. Fields of the invention
The present invention relates to an auxiliary drive assembly, especially to an auxiliary drive assembly for wheelchairs.
2. Descriptions of Related Art
The progress of medical science has been so rapid that people are living longer than ever now. However, people's main organs are aging and their illness is increasing as they age. When people are sick or getting older and weaker, they are confined to beds for a long period time. This leads to disability, physical deconditioning and even bedsores. The cardiorespiratory function, large intestinal motility and the urinary system are also affected. Thus older people and handicapped people badly need mobility aids such as wheelchairs to help them move around. Wheelchairs are ideal mobility aids for the elder and the handicapped so that they can operate the wheelchairs and move independently. Thereby the convenience and safety of the wheelchair users are quite important. Most of wheelchairs available now are convenient for users to travel and having controllers for control of wheelchairs easily.
There are various types of wheelchairs. According to power sources, wheelchairs are divided into two groups-manually operated wheelchairs and electric wheelchairs. The manually operated wheelchair is run by operating a ring under an armrest of the wheelchair for driving a wheel and moving the wheelchair forward. As to the electric wheelchair, it is a wheelchair powered by an electric motor and users only need to operate a control device for adjusting direction and speed of motion. Thus the electric wheelchair is a mobility aid device that makes the movement more comfortable for users. However, users in such wheelchairs will lose the advantage of the exercise they would get pushing the manually operated wheelchairs.
Based on the reasons mentioned above, an auxiliary drive assembly for manually operated wheelchairs that enable users move the wheelchairs easily has been developed. The force users applied to the wheelchairs is detected by a force sensor so as to generate a sensing signal that is sent to a control circuit by wiredless transmission. According the sensing signal, the control circuit drives the motor for propelling wheelchair wheels and users can push the wheelchairs easily. Conventional wheelchairs with power aids do enable users to push wheelchairs easily and signals are transmitted in a wiredless way in such power aids. However, wiredless communications are very susceptible to environmental interference. Once the sensing signals are not transmitted to the control circuit precisely, the control circuit can't drive the motor properly in response to the sensing signals and users get no assistance. Moreover, the structure of conventional auxiliary drive devices for wheelchairs is complicated. Together with wiredless transmission devise, the total cost is quite expensive.
In order to overcome the above shortcomings, there is a need to provide an auxiliary drive assembly for wheelchairs that provides users assistance so that users can move the wheelchairs with reduced energy. Moreover, the present invention has a simple structure and signals are transmitted in a wired way. Thus the cost is reduced and signals are transmitted without interference in the environment. The sensing signals are sent back precisely while users moving the wheelchairs and the wheels of the wheelchairs are propelled so as to provide assistance during the movement of the wheelchairs.